Hitherto, to heat a heated material of food, etc., first the heated material has been placed in a heating chamber, a high-frequency heating switch has been pressed for starting heating, and when the specified predetermined time has elapsed or the heated material has reached a predetermined finish temperature, the heating has been stopped and then the heated material has been taken out. However, a heated material generating steam as the material is heated is deprived of moisture by high-frequency heating, and the surface of the heated material is dried or hardened. Then, to suppress a decrease in the moisture content by high-frequency heating, for example, the heated material is wrapped in wrap film (thin film for wrapping food) and heating treatment is performed so that steam does not escape.
As the heating conditions of the heating time, the output value of high-frequency heating, etc., for example, the weight of the heated material is detected and the condition is controlled to the heating amount matching the weight, or the temperature of the heated material during heating is detected by an infrared sensor and the condition is controlled so as to prevent overheating.
Further, the conventional high-frequency heating apparatus include a microwave oven including a high-frequency generator for heating, a combination cooking range including a convection heater for generating a hot wind, added to the microwave oven, and the like. A steamer for introducing steam into a heating chamber and heating, a steam convection oven including a convection heater added to the steamer, and the like are also used as cooking utensils.
To cook an article of food, etc., with the cooking utensil, the cooking utensil is controlled so that the heated finish state of the food article becomes the best. That is, cooking using high-frequency heating and hot-wind heating in combination can be controlled with a combination cooking range and cooking using steam heating and hot-wind heating in combination can be controlled with a steam convection oven. However, cooking using high-frequency heating and steam heating in combination involves time and labor of performing each heat treatment with the heated food transferred between separate cooking utensils. To eliminate the inconvenience, one cooking utensil that can accomplish high-frequency heating, steam heating, and electric heating is available. This cooking utensil is disclosed, for example, in Japanese Unexamined Patent Publication No. Sho 54-115448.
However, it is bothersome for the operator to wrap a heated material in wrap in each heating, and caution needs also to be taken in removing the wrap at the heating termination time from the viewpoint of the heated material at a high temperature, resulting in burdensome heating work. Then, various types of high-frequency heating apparatus with a steam generation function in addition to a high-frequency heating function are considered. According to such a high-frequency heating apparatus with a steam generation function, high-frequency heating is performed with a heating chamber filled with steam, whereby the heated material can be heated without depriving the heated material of moisture; on the other hand, if the heating chamber is filled with steam, an infrared sensor measures the temperature of the filled steam particles and it is made impossible to accurately detect the temperature of the food; this is a problem.
In a high-frequency heating apparatus of turn table type, a weight sensor is attached to the rotation shaft of a turn table for measuring the weight of a heated material, and optimum heating treatment responsive to the weight of the heated material is conducted. On the other hand, a technique is available wherein a high frequency generated by a magnetron is applied to a rotated stirrer blade and is spread into a heating chamber for the purpose of effectively using the inside of the heating chamber. In this technique, the heated material is placed directly on the bottom of the heating chamber and thus a weight sensor as in the turn table type cannot be attached and therefore a problem of incapability of directly measuring the quantity of the heated material occurs.
Further, in a cooking utensil provided with a temperature sensor such as an infrared sensor for measuring the temperature of a heated material, if a heating chamber fills with steam, the infrared sensor measures the temperature of the suspended particles of the steam existing in space with the heated material rather than the temperature of the heated material, as described above. Thus, it is made impossible to precisely measure the temperature of the heated material. Then, heating control performed based on the temperature detection result of the infrared sensor does not normally operate and a defective condition of insufficient heating, successive heating, etc., for example, occurs. Particularly, to perform automatic cooking in a sequential procedure, the procedure proceeds to the next step as the heat failure remains; simple re-heating, standing to cool, etc., cannot overcome it and there is also a possibility that the cooking will result in failure.
As a control method for cooking with steam heating and high-frequency heating in association in the publication, the point of switching from high-frequency heating to steam heating and the point of performing both the steam heating and the high-frequency heating at the same time only within a predetermined time at the switching time. However, the disclosure of the publication does not reach the level at which an appropriate heating program is automatically selected and executed in response to the type of object to be heated. Therefore, if a plurality of heating programs are provided, the operator must determine which heating program is to be selected for cooking.
When steam heating and high-frequency heating are performed at the same time, the amount of electric power for heating increases and thus most of rated power is consumed for the high-frequency heating and the amount of electric power for the vapor heating essentially required cannot be covered. Therefore, insufficient steam heating can only be performed and a restriction is placed on the cooking; this is a problem. Thus, as shown in FIG. 38, often, in fact, each heating is switched on and off in a short time under pulse control, thereby suppressing the instantaneous total used electric power (amount of electric power for steam heating, a, +amount of electric power for high-frequency heating, b). However, each heating becomes intermittent and thus the heating efficiency is degraded and it is made impossible to make full use of the essential heating capability. Consequently, the heating time increases and the total power consumption also tends to increase.
The user may visually check the heated material for the heated condition through a window of a door of a heating chamber. Particularly, to perform steam heating, condensation occurs on the window and often it is made impossible for the user to peep into the heating chamber; it is feared that the ease of use may be degraded.
It is therefore an object of the invention to provide a heating control method of a high-frequency heating apparatus and the high-frequency heating apparatus for making it possible to supply steam to a heating chamber, perform high-frequency heating, and precisely detect the heating temperature of a heated material by an infrared sensor.
Further, an object of the invention to provide a control method of a high-frequency heating apparatus with steam generation function for making it possible to perform appropriate heating treatment by measuring the temperature of a heated material precisely, automatically select an optimum heating program in response to the type of heated material, ensure the maximum heating efficiency within rated power, and enhance the ease of use.